Extension ladders



Sept. 2, 1969 H. KRAMER 3,464,522

EXTENSION LADDERS Filed Aug. 25, 196'. 2 sheets-sheet 1 INVENTOR/fyM/y/v KRF/V15?,

ATTORN EY Sept. 2, i969 H, KRAMER EXTENSION LADDERS 2 Sheets-Sheet 2Filed Aug. 25. 1967 INVENTOR BY I ATTORNEY tate 3,464,522 EXTENSONLADDERS Hyman Kramer, 2764 E. 16th St., Brooklyn, NX. 11235 Filed Aug.25, 1967, Ser. No. 663,234 int. Cl. E06c 7/06 U.S. Cl. 132-211 12 ClaimsABSTRACT F THE DISCLOSURE This invention relates to improvements inextension ladders and more particularly to improvements therein havingto do with the mounting and/or biasing of the stop hooks thereof andwith the construction of the stophook retracting levers, sometimes alsocalled slip-by levers.

To assist in a proper understanding of the objectives of the invention,it is explained that whereas the pivoted stop hooks which, by hooking tothe rungs of the relatively xed lower section of an extension ladder,function to secure the upper section thereof in raised position, are intheory mounted to swing in planes disposed closely adjacent to but ofcourse spaced from the inner faces of the side rails of said uppersection, such for a variety of reasons is not always the case. Forexample, the economics of manufacturing extension ladders do not alwayspermit of the stop hooks being mounted with the precision required toinsure their movement in fixed planes which are invariably spaced fromthe inner sides of the side rails of the upper section. Again, extensionladders in use are sometimes subjected to rough handling and such maycause either or both of the stop hooks incorporated therein to becomebent or even twisted slightly out of their normal shape and, when suchconditions prevail, the bent or twisted hook or hooks may rub on theinner surfaces of the upper-section side rails to the degree marring ifnot damaging said surfaces and impeding the free and easy swingingaction of the stop-hooks between their active and retracted positions,as is necessary to the smooth and certain operation of said stop hooks.Obviously, the likelihood of the stop hooks marring the inner surfacesof upper-section side rails increases if the stop hooks are formed asmetal stampings provided for strength with marginal flanges and aremounted with their recessed faces disposed towards said side faces,rather than being formed as relatively smooth-faced castings.

An important object of the present invention, therefore, is theprovision of improved means for mounting the stop hooks of extensionladders which functions positively to prevent the hooks rubbing on theinner sides of the side rails of the upper section of such a ladder asthey partake of their swinging motion between their normally active andtheir retracted positions.

atent O W 3,464,522 Patented Sept. 2, 1969 ACC More particularly, in theaspect of the invention under consideration, the invention contemplatesand provides an improved hook-mounting fixture capable of readyattachment to the side rails of the upper section of an extensionladder, which serves the plural functions of effectively mounting thestop hooks employed in such a ladder so that they may swing betweentheir active and retracted positions as required, of spacing the hooksrelatively inwardly away from the inner side surfaces of the side railsmounting same thereby insuring that said stop hooks will not rub againstsaid side surfaces as they partake of their swinging mot-ion, ofsupporting and guiding the hooks in manner as insures that they willinvariably swing in their intended planes, and, finally, assuming thatthe hooks are of the type which are springbiased to their normallyactive position, of providing both a novel simplified mounting and ahousing for the biasing spring associated with each stop hook.

As to another aspect of the invention which relates to the constructionof the stop-hook retracting or slip-by levers, it is explained thatnormally such levers are made righthand and lefthand, just as the stophooks themselves are made righthand and lefthand, and thus they cannotbe used interchangeably with righthand and lefthand stop hooks. Suchnon-interchangeability of the levers was previously reflected inincreased cost of ladder manufacture since the righthand and lefthandlevers had to be individually fabricated and inventoried and such alsointroduced some difficulties in the use of ladders in the eld in theevent replacement of one of the levers should be required.

Accordingly, the invention in this aspect thereof contemplates andprovides an improved design of stop-hook retracting or slip-by leverwhich enables it to be used interchangeably with both righthand andlefthand stop hooks. Thus, one and the same lever may be usedinterchangeably as a rightside or leftside lever, which of courseintroduces economies in ladder manufacture since only one design orstyle of lever need be inventoried.

The above and other objects and features of advantage accuring from theimprovements of the invention will bcome apparent from a considerationof the following detailed description thereof, taken with theaccompanying illustrative drawings, wherein FIG. 1 is a fragmentarypart-sectional view looking towards the inner sides or faces of the leftside-rails of the sections of an extension ladder incorporating theimprovements of the invention and showing an improved stop-hook mountingand biasing means of the invention in front elevation;

FIG. 2 is a section taken along line 2-2 of FIG. l;

FIG. 3 is a section taken along line 3-3 of FIG. 1;

FIG. 4 is a view similar to FIG. 1 which illustrates the hook-retractingaction of the lever shown in FIG. 1 which enables its associated stophook to slip by the rungs of the lower ladder section when it is desiredto lower the upper section of the ladder with respect to said lowersection thereof;

FIG. 5 is a broken-away perspective view illustrating the capability ofthe stop-hook retracting levers of the invention each to serve either asa right-hand or left-hand lever;

FIG. 6 is a perspective view showing a sub-assembly of a stop-hookmounting fixture, stop hook, stop-hook pivot and stop-hook biasingspring prior to the assembly thereof to the side rail of the uppersection of the ladder with which the stop-hook is to be associated; f

FIG. 7 is a section of the mounting fixture taken along line 7-7 of FIG.6;

FIGS. 8 and 9 are sections corresponding to that shown in FIG. 7 buttaken through modified forms of stop-hook mounting fixture; and

FIG. l is a perspective view similar to FIG. 6 which illustrates amodified sub-assembly of fixture, stop-hook, stop-hook pivot and hookbiasing spring, wherein the fixture has variant form as compared toVthat employed in the FIG. 6 sub-assembly.

Referring to the drawings in greater detail, an extension ladder forwhich the improvements of the present invention were devised basicallycomprises lower and upper ladder sections designated A and B,respectively, each made up of the side rails 10, 12 and associated crossrungs 14, 16 (of which only the left-side rails are shown). Near itslower end, the upper section B mounts a pair of stop hooks 18, 20 (bothof which are partially shown in FIG. which are adapted to swing inplanes closely adjacent the inner-sides or faces of the upper-sectionside rails to which they are mounted between their active lockingpositions, in which they are adapted to hook over a cross rung 14 of thelower section (full lines, FIG. 1), and their retracted position inwhich they clear the rungs of the lower section A of the ladder (brokenlines, FIG. 1).

Each of the stop hooks pivotally mounts via a pivot pin 26 a retractingor slip-by lever, such being generally designated 22, 24 in FIG. 5,whose action is first to close the openings of the hooks and thereuponto effect the retracting movement of said hooks to a rung slip-byposition, as permits lowering of the ladder section B with respect tothe lower fixed section A when such is desired, in manner wellunderstood in the art.

By reference to FIG. 2 which illustrates preferred side railconstruction, it will be seen that the aforesaid side rails 10, 12 arefashioned from metal, preferably a lightweight metal such as aluminum ormagnesium, and that such have shallow channel construction, with thechannels being provided with inwardly turned side flanges or beadsdesignated b, 12b which interlock when the upper section of the ladderis assembled to the lower section thereof. It will be understood,however, that the improvements to be described are not limited toladders whose side rails and rungs are made of metal (commonly referredto as aluminum ladders), since the herein irnprovements are equallyuseful when applied to the older style ladders whose side rails andrungs are of wood.

With the exception of the detailed construction of said retractinglevers 22, 24 which will be later described, the extension ladderconstruction so far described is conventional.

According to an important aspect of the present invention, the aforesaidstop-hooks 18, 20, which illustratively are of the type which arespring-biased towards their locking position shown in FIG. l, are somounted that in partaking of their swinging movement between active andretracting positions, they are positively prevented from rubbing againstthe inner side faces of the side rails of the upper section to whichthey are mounted. More particularly, rather than being pivotallyconnected directly to said upper-section side rails so that they mustswing in planes closely adjacent the inner-side faces thereof, as isconventional, they are instead pivotally connected to mounting fixturessecured to the side rails which perform the manifold functions ofdisposing their swing planes an appreciable distance inwardly of theside-rail inner faces; of providing confining and guiding surfaces forthe lower or shank ends of the hooks which in large measure insureagainst said ends twisting or slewing about their pivots even though theladder is subjected to rough handling in use; and, assuming that thestop hooks are spring-biased to their `active position, of mounting andhousing the springs which so bias said stop hooks.

A mounting fixture capable of performing the aforesaid functions maytake the various physical forms illustrated in FIGS. 6-10, for example,with all such forms having the common features of being of modifiedchannel section and of incorporating means providing for readilyafiixing same to the inwardly facing side or wall of a ladder side rail,in position such that the channel thereof extends vertically and isclosed on its normally open side by the side rail to which the fixtureis affixed. More particularly, the mounting fixture 30 shown in FIG. 6has a body of channel section, as defined by laterally spacedapart sidewalls 32, 34 and a flat bottom wall 36 extending therebetween. Bydesign, the width and depth of the channel provided by said side andbottom walls is substantially greater than the width and thickness,respectively, of the shank end of the stop hook (1S or 20) which is tobe mounted by said fixture. Thus, the channel of the fixture bodyprovides for the ready reception of said shank end, and said fiat bottomwall 36 of the fixture is adapted to provide a rigid wall or surfacewhich is spaced inwardly from the side rail to which the fixture issecured (by inwardly is meant in the direction of the opposite siderail) a distance which is appreciably greater than the thickness of thestop-hook shank portion and to which the stop hook may be pivotallysecured. According to the invention, the shank end of the stop hook,following its insertion into the fixture channel through an open endthereof to a housed position therein, is pivotally connected to thefixture bottom wall 36 for bodily swinging movement relative to saidfixture by means of a pivot bolt 38 (FIGS. 3 and 6) which is projectedthrough an opening provided therefor in the side rail with which thefixture is associated. Said bolt 38 is secured in place as by a nut 38athreaded thereon, the bolt thus serving as a hook pivot and as a meansfor securing the fixture 30 to its associated side rail.

Preferably, each fixture 30 is provided with means in addition to saidpivot bolt 3S for locating it on its side rail asaforesaid.Illustratively, such means comprises L- shaped hooks 42a, 42bwhich project from the relatively upper-end corners of the fixture sidewalls 32, 34 and straightway projecting tabs 44a, 441) projecting fromthe opposite corners of said side walls. The inner wall of each siderail to which a fixture is to be mounted will be punched with aperturesarranged for the insertion of said hooks and tabs and, when suchinsertion has been effected, the tabs 44a, 4417 may be inturned as shownin FIG. 2, thus to lock the fixture body to said side rail.

When a stop hook is pivotally connected to the bottom wall 36 of achannel-section fixture 30 in the manner just described and with nothingmore than the pivot 38 to hold it in its intended plane of motion, it isquite possible for the hook to slew or twist out of said plane andshould this occur it would in large measure defeat a major objective ofthe invention. To prevent any such objectionable slewing or twisting,the fixture body incorporates strap means spaced relatively upwardlyfrom the point of pivotal connection of hook to fixture as defined bythe pivot bolt 38, which functions, in concert with the bottom wallproper, both to confine and to guide the hook so that it is free toswing only in is proper plane of motion. Such means illustrativelycomprises a cross strap generally designated 46 which extends betweenthe side Walls 32, 34 of the fixture body intermediate the ends thereofand at a level such that the relatively outer surface of said strap isspaced from the under surface of the fixture bottom 36 by an amountsubstantially equal to the thickness of the stop hook received in thefixture channel.

As seen in FIG. 7, said cross strap 46 may be formed by two likehalf-length strap sections 46a, 4611 comprising areas struck out fromthe bottom and side walls of the fixture, but said cross strap may alsobe formed as a unitary crosswise-extending strap struck or drawn outfrom the metal of the xture body, with any excess metal being taken upby a single deep U-bend 48 (FIG. 8) or by plural U-bends 48a, 481? (FIG.9) of lesser depth. But regardless of how formed, the cross strap 46,acting in concert with the bottom-wall end sections 36a, 36b whichremain following fashioning of the cross-strap therefrom, provideopposed vertically spaced, transversely extending strap-like guiding andconfining surfaces for the hook shank pivotally connected to the bottomwall section 36a by the pivot 38 as aforesaid and which, by being spacedapart a distance corresponding substantially to the thickness of saidshank portion, maintain the hook mounted by the fixture in its properplane during the course of its movements between active and retractedpositions.

As forecast above, and this assumes that the stop hooks 18, 29 mountedvia their mounting fixtures 30 as described are spring-biased to theirrespective active or rung-hooking positions, each said fixture alsoincorporates means for mounting and housing the spring which biases thestop hook mounted thereby. More particularly, and now referring to FIGS.l and 6, a hook-biasing spring 50` as herein contemplated preferablycomprises a simple leaf spring whose lower end is affixed to the innerside of the relatively rearward side wall 32 of the fixture and whoseupper free end which inclines relativelyforwardly engages on therearward edge of the hook shank extending into said fixture, thus topress or bias same and thereby the entire hook in forward direction.

The means for affixing the lower end of each leaf spring 50 to thefixture side wall 32 as aforesaid is best shown in FIG. 6, and comprisesan indented slot-like eye formation generally designated 52 sunk intosaid side wall near its lower edge and having width and depth as tosnugly receive the lower end of the leaf spring when the latter isprojected thereinto. Illustratively, said eye formation is provided byincising said wall with two parallel cuts or slits a, b and thereafterpressing the area of the side wall extending between the slits inwardlyso that it forms a strap extending generally parallel to the innersurface of said side wall, whereupon the slits define eye openings. Thespring end to be cooperated with said eye formation 52 is formed with anoutwardly projecting dimple 50a which, upon insertion of the spring endin said eye formation, locks the spring in place, by reason of itsability to lockingly abut the edges of the silts which define the eyeopenings.

By providing an eye formation 54 corresponding in all respects to theaforesaid eye formation 52. in the opposite side wall 34 of the fixturebody, and by arranging the aperture which is provided in the bottom wall36 of said fixture body for the pivot bolt 38 on the longitudinal centerline of said body, as results in the fixture being symmetrical to bothsides of its longitudinal center plane, the one and the same fixture canbe used interchangeably to mount either a righthand or lefthand stophook.

While also characterized by a fixture body of channel section, themodified form of fixture illustrated in FIG. differs from the FIGS. 6-9forms of fixture in providing for the mounting of the stophook shankexternally rather than internally of the channel thereof. Moreparticularly, the modified fixture body designated 60- shown in FIG. 10and which is defined by spaced-apart side walls 62, 64 and a bottom wall66, is adapted toreceive and secure the shank end of a stop hook laidsubstantially flat against the outer face of said bottom wall andprojecting into the space between said outer face and the effectivelyopposed under face of a saddle-like cross strap 68 preferably deepdrawnout of the material of said bottom wall. Thus, said cross strap 68,rather than the channel bottom-wall 66, provides the fixed part for thepassage of the pivot 70 which pivotally connects the stop-hook shank andthereby the stop-hook proper to the fixture body 6() and via saidfixture body to the side rail to which said fixture body is fixed bysaid pivot bolt. The aforesaid modified fixture 60 thus acts not only topositively space the shank end of a stop-hook mounted thereby relativelyinwardly from the inner face of the ladder side rail to which it issecured, but also to confine and guide said shank end so that it canswing only in a fixed plane which is the plane normal to the axis of thepivot bolt 7 0.

It will also be seen from a consideration of FIG. l0 that the side walls68a, 68b of the saddle-like cross strap 68 can be and are shown to beprovided with eye formations 72, 74 comparing in all substantialrespects with the eye formations 52, S4 of the FIG. 6 form for thereception of a hook-biasing spring 74 also comparing to the aforesaidhook-biasing spring 50 of the FIG. 6 form. Thus, while differingsomewhat in structure, the modified fixture body 60 according to FIG. 10performs the same functions as the fixture body 30 shown in FIG. 6.

At this point of the description, it is noted that the fixture bodies 30and 60 are each shown to be provided with notches designated 30x and 60xin the upper edges of their side walls. Such notches serve to receiveand anchor the ends of the I -shaped springs (not shown) conventionallyemployed to bias extension ladder stop hooks to their active position,should such be used in place of the leaf-spring biasing means of thepresent invention, for example, to exhaust a supply of such J-shapedsprings.

Corning now to the improved construction of stop-hook retracting levercontemplated and provide by the present invention, it is first explainedthat while the curved cam edges C with which the extension ladder stophooks 18, 22 are each conventionally provided function by engagementthereof with the rungs of the lower ladder section A to effectsuccessive retractions of the stop hooks from their corresponding activeposition (full lines, FIG. l) to their retracted or inactive position(broken lines, FIG. l) during the course of the ladder being lengthenedor extended, said hooks each also pivotally mounts its aforesaidretracting lever (22 or 24) which, when swung to its hook-closingposition responsive to its being lowered against a rung of the fixedlower section of the ladder (full lines, FIG. 4), also effectssuccessive retractions of the stop hooks to their full retractedposition (broken lines, FIG. 4), as permits shortening of the ladder tomeet varying use conditions or the complete collapse of the ladder fortransport or storage. Previously, the retracting levers serving thisfunction were so configured as to permit their assembly on either aright-side or left-side stop hook but not on both; that is to say, saidretracting levers as previously constructed were of either fixedright-hand or left-hand construction and hence could not be usedinterchangeably on right-side or left-side stop-hooks.

According to the present invention7 the construction of thehook-retracting levers 22, 24 is such that one and the same lever can beused interchangeably with either a right-side or a left-side stop hookof the type designated 18, 20 and, since but a single lever constructionis contemplated, a description of one such lever will sufiice for both.More particularly, and referring to FIGS. l, 4 and 5, a stop-hookretracting lever according to the invention comprises, in the rstinstance, a sheet-metal stamping configured to provide a planar,vertically disposed, rearward tail portion and a similarly verticallydisposed, co-planar arm portion 162 extending forwardly therefrom; andprojecting forwardly from said arm portion a rungand hook-engaging tipportion 104 which is generally horizontally disposed and extendslaterally and symmetrically to opposite sides of the common verticalplane of said tail and arm portions.

As is best seen in FIG. l, such a stop-hook retracting lever is of thebalanced type so that it will normally assume a generally horizontalposition. Accordingly, its pivot or fulcrum point, as determined by theaforesaid pivot pin 26 which secures it to its stop lever 1.8 or 20 isdisposed near its geometric center, and the area of its rearward tailportion will by design be such as to provide the necessary weight asbalances the weight of the forward arm and rungand hook-engaging tipportions thereof.

As further seen in FIG. 5, the rungand hook-engaging tip portion 104 ofeach said lever 22, 24 and which is shown to be integrally connected tothe arm portion of said lever by an offset web 108 has substantialwidth, being preferably somewhat greater than twice the width of thefree or nose end of a stop hook. Thus, and because said tip end extendssubstantially equal amounts to both sides of the common plane of thelever proper, it is adapted when moved towards the nose end of its stophook to engage said nose end and thereby close the opening of the stophook to which it is assembled, regardless of whether said hook is ofright-side or left-side construction.-

FIG. further illustrates the preferred curvature applied to the tip ends104 of the stop-hook retracting levers. More particularly, said tip endis formed with upwardly concave-downwardly convex curvature, with theresulting convexity and concavity extending transversely across said tipend. Accordingly, when the ladder is being lengthened by upward movementof the upper section B, the concave upper surface of the tip ends of thelevers 22, 24 will glide on the curved under peripheral surface of therungs of the lower section engaged thereby without undue friction.Conversely, when the ladder is being lowered or collapsed, assuccessively brings the downwardly convex under surfaces of theretracting-lever tip ends into engagement with the curved upperperipheral su-rfaces of the rungs of said lower section, smooth and easyoperation of the retracting levers is assured.

Although the like tip ends 104 of the levers 22, 24 have been shown inFIG. 5 to extend integrally in the transverse direction from andsymmetrically to the sides of the common planes of said levers, othertip-end constructions performing the same or substantially the samefunctions as that shown are possible. For example, each tip end 104 maybe formed by physically separate wings or part sections which extendfrom opposite sides of its lever proper, and said oppositely extendingwings may be disposed at dierent levels rather than at the same level,as shown.

Without further analysis, it will be appreciated that the improvementsin extension ladder construction and design according to my presentinvention provides refinements both in the mounting means for thestop-hooks as employed in such extension ladders and in the design andconstruction of the stop-hook retracting levers. FIGS. 6 and l0 alsomake clear yet another advantage accruing from 4the improvedstop-hook-mounting means as herein proposed, namely, that stop-hooks,the mounting means therefore, the springs which normally bias the stophooks to their active or rung-hooking positions, and the pivot bolts forthe stop hooks, may be fabricated complete and inventoried assub-assemblies for sale to extension ladder manufacturers, thus enablingthe latter to complete the fabrication of extension ladders as sold witha minimum of manufacturing time and labor costs.

However, as many changes could be made in carrying out the aboveconstructions without departing from the scope of the invention, it isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

I claim:

1. An extension ladder comprising upper and lower relatively extensibleladder sections, each comprising laterally spaced side rails andvertically spaced rungs eX- tending transversely therebetween; at leastone stop-hook carried by the upper section and adapted to swing in aplane substantially parallel to that of an upper-section side railbetween active and retracted positions and in its active position tohook over a selected rung 0f the lower section thereby to secure theupper section in extended position with respect to the lower section;means affixed to the inner face of said side rail of the upper sectionand including a first part providing a first rigid surface which isspaced inwardly from said rail inner face by an amount insuring thatsaid hook when lying thereagainst will not rub against same during thecourse of its swinging movement and a second part providing a secondrigid surface spaced from but operatively related to said first surfacefor confining and guiding said hook in its movement aforesaid; one ofsaid parts comprising an area removed from said other part and extendingparallel thereto; and a pivot connecting the hook to said first part inposition Such that it lies against said first surface and also forbodily affixing said means to said side rail.

2. An extension ladder according to claim 1, wherein said meanscomprises a fixture of channel section defined iby spaced-apart sidewalls and a bottom wall and being afiixed to said side rail in positionsuch that its channel extends vertically and is closed on its normallyopen side by said rail, whereby said bottom wall is spaced relativelyinwardly from said side rail; and -wherein said bottom wall providessaid first and second parts and their said rigid surfaces.

3. An extension ladder according to claim 2, wherein the shank end ofthe hook extends into said channel and lies against the under side ofsaid bottom wall, and wherein said pivot pivotally secures said shankend to said bottom Wall.

4. An extension ladder according to claim 2, wherein the shank end ofthe hook is positioned against the outer side of said bottom wall.

5. An extension ladder according to claim 1, wherein said means isfashioned throughout from sheet metal and said one part comprises anarea struck out from said other part.

6. An extension ladder according to claim 1, wherein said part providingsaid second rigid surface comprises a cross strap afiixed to andextending transversely across said part providing said first rigidsurface and being spaced therefrom a distance substantially equal to thethickness of the hook shank, the construction and arrangement being suchthat said cross strap holds the hook shank against said first rigidsurface as it moves across said space and thereby guides the hook as itswings.

7. An extension ladder according to claim 2, wherein said fixture mountsand provides for the enclosure thereof within its channel spring meanswhich biases the hook to its active position.

8. An extension ladder according to claim 7, wherein said spring meanscomprises a leaf spring having one end fixed to a channel side wall andthe other end free and being disposed in said channel so that its freeend engages an edge of the stop-hook.

9. An extension ladder according to clairn 8, wherein the means forfixing said one end of the spring comprises an indented eye formationprovided in said channel side wall for the reception of said one end,and spring locking means formed on said spring for locking the springend when it is received in said eye formation.

10. An extension ladder according to claim 9, wherein said springlocking means comprises a dimple pressed out of the material of said oneend and being positioned to lock against the edges defining said eyeformation.

11. In an extension ladder comprising upper and lower relativelyextensible ladder sections, each comprising laterally spaced side railsand vertically spaced rungs extending transversely therebetween,rightand left-side stop hooks pivotally -mounted on the side rails ofthe upper section for swinging movement fbetween normally active andretracted positions in planes that are spaced small distances relativelyinwardly from the inner-side faces of said side rails, the improvementcomprising hook-retracting levers pivotally mounted on said hooks foreffecting retraction thereof when shortening of the ladder is desired,said levers being of identical construction and fashioned throughoutfrom sheet metal, each said lever comprising a rearward tail portion, aforward arm portion and a tip portion projecting forwardly from said armportion, all said portions being integral one with the other and saidtail portion having weight substantially equal to the combined weight ofsaid arm and tip portion, said tail and arm portions being co-planar anddisposed vertically, said tip portion being disposed generallyhorizontally and extending laterally and symmetrically to both sides ofthe common plane of said tail and arm portions, thereby to providerungand hook-engaging surfaces which also extend laterally andsymmetrically to both sides of the lever proper.

12. An extension ladder according to claim 14, wherein said tip portionis upwardly convex immediately adjacent its arm portion and downwardlyconcave distally therefrom, and wherein the resulting convexity andconcavity extend transversely across the tip portion.

References Cited UNITED STATES PATENTS 532,700 l/l895 Possin 182-210864,194 8/1907 Reimann 182-211 719,449 2/ 1903 Ferguson 182-2111,244,645 10/ 1917 Schreiner 182-210 2,942,686 6/1960 Osovski 182-209REINALDO P. MACHADO, Primary Examiner

